Control switch for calculating machines



June 5, 1945. T o, ME A 2,377,707.

CONTROL SWITCH FOR CALCULATING MACHINES Filed Oct. 1, 1940 v 5 Sheets-Sheet l 1 g im- 0 O (D G C) 00 (DC) QC) 0 v IN ilih.

lllllllllllll June 5,' 1945.

T. O. MEHAN CONTROL SWITCH FOR CALCULATING MACHINES Filed Oct. 1, 1940 5 Sheets-Sheet 2 J72 v2 nor: 250mm; 0 Mefian B June 5, 1945. T10. MEHAN CONTROL SWITCH FOR CALCULATING MACHINES Filed Oct. 1, 1940 5 Sheets-Sheet 3 7720mm GHQ/care .9 7 Wm, d

June 5, 1945. T. o. MEHAN CONTROL SWITCH FOR CALCULATING MACHINES 5 Sheets-Sheet '4 Filed Oct. 1, 1940 B 0%? V H 9.???

I I June a, 1945. T. o. MEHAN CONTROL SWITCH FOR CALCULATING MACHINES Filed Oct. 1. 1940 5 Sheets-Sheet 5 kfizaaeni'ar: 4 T/zamas 0. fife/awn By 6/" I Patented June 5, 1945 1 UNITED STAT S PATENT OFFICE CONTROL SWITCH FOR CALCULATING .MACHINES Thomas 0. Mehan, Park Ridge, Ill., assignor to Victor Adding Machine 00., Chicago, 111., a corporation of Illinois Application October 1, 1940, Serial No. 359,271

7 Claims.

My invention relates generally to calculating machines, and more particularly to improved control switch mechanisms forming parts or such machines.

it is an object of my invention to provide an improved switch means for controlling the operating cycle of an adding machine.

A further object is to provide an improved long useful life.

Othcrobjects will appear from the following description, reference being had to the accentpanying drawings, in which:

Fig, 1 is a fragmentar plan view of the calculating machine, showing particularly the key' hoard portion thereof;

Fig. 2 is a right-side elevational view oi a portion of the motor control mechanism, the outor casing being shown in section;

Fig. 3 is an enlarged obliquely vertical sectional view taken on the line 3--3 of Fig. 2 and v showing particularly the solenoid control switch and associated mechanism;

Fig. 4 is a vertical longitudinal sectional viewtaken on the line ll--4'of Fig. 3 and showing particularly the control keys;

Fig. 5 is a fragmentary vertical sectional view to a reduced scale, showing the means for releasing the key latching slides;

Fig. 6 is a generally horizontal sectional view taken on the line 66 of Fig. 4 and showing particularly the control slides operated by the key stems;

Fig. 7 is a generally horizontal sectional view taken on the line 'il of Fig. 4 showing particularly the additional slides operated by the control keys;

a whole. provided for this purpose.

construction and operation of the apparatus as The following general description is The invention may be incorporated in any suitable electric motor-operated adding, calculating machine, or the like, but is illustrated herein as forming part of an adding machine. In gen.-

' eral, referring particularly to the wiring diagram Fig. 8 is a fragmentary vertical sectional view taken on the line 8-8 of Fig. 3; and

Fig. 9 is a wiring diagram showing the motor control circuits.

General description It is believed that the detailed' description or the invention will be more readily understood it it is read with a. knowledge of the general 56 solenoid 28) during the course of each operating oi Fig. 12, the apparatus comprises a motor 2d adapted to drive the adding machine through a one-revolution clutch mechanism. The motor is,

adapted to be energized by depression of a motor bar 54 which, when depressed, closes a switch N. The switch 24 is adapted to complete a circuit from power supply conductors 26, 21, through the winding of a solenoid 28 and a normally closed switch 30. Energization of the solenoid 28 causes its core to move to the left, Fig. 12, and through an arm 32, link 34, and lever 36, opens the switch 3H and closes a switch 38. The switch 38 is connected between the conductor 26 and a conductor it through which current is supplied to the motor 2%. The return circuit from the motor is through the conductor 27.- A condenser 42 is associated with the motor to aid in reducing sparking across its speed governor contacts.

A switch 44 is connected in. parallel with the switch 24, and is adapted to he closed for an instant each time anyone of a plurality of control keys, designated generally by the reference character 46, is operated. The control keys 4% determine the character of the operation of the machine, these keys bearing appropriate legends in Fig. 1, being identified by individual reference characters as follows: 86.l-"NP-non-print; l8.2--NA-non-add; 46.3ST-2sub-total second accumulator; 46.4--T-2total second accumulator; 46.5ST-1-sub-total first accumulator; 48.6-T- -sub-total first accumulator; IL-CR. BAL.--credit balance; 46.8- REP."-repeat; lit-(ERRP-error.

From the foregoing description of thecircuit diagram (Fig. 9),, it will appear-that when either the switch 24 or the switch 44 is closed, the solenoid 28 will be momentarily energized to complete the circuit to themotor 20. Upon operation o! the motor 20, the lever 36 will be mechanically held in a position in which it maintains the switch 30 open and the switch 38 closed until at least one revolution of the main operating shaft has been completed. The lever 3'6 forms the trip lever of a suitable one revolution clutch mechanism, and is mechanically returned to normal position (thus pulling the core 84 from the cycle of the machine. This one revolution clutch mechanism forms the driving connection between the motor 20 and the main shaft of the machine, and is eilective to rotate the latter through one revolution upon energization of the solenoid 28.

The keyboard and motor bar As shown in Fig. l, the machine comprises a casing 43, which may be of any suitable construction, and banks of numeral keys 45. In addition, there are provided add and subtract control keys 41 for the second accumulator, these keys bearing the appropriate legends "2A and 25, but which will usually be differentiated by being of different colors. A release key 46 is provided for the two keys 41. A subtract key 50 is provided to condition the machine for subtracting on the first accumulator.

The manually operated means for controlling the operation of the motor in normal adding and subtracting operations comprises a pair of rigid generally U-shaped bars 52 and 64, together forming a rectangle entirely surrounding the keyboard. The ends of the bar 52 are joined by a transverse member 56 to increase the rigidity of the bar 62. The bar 62, as shown in Fig. 2, is pivoted upon a pair of shouldered screws 56 threaded in lugs forming part of a key plate 66. (The screw 58 at the left-hand side of the motor bar 52 is not shown in the drawings.) Similarly, the key bar 54 has rearwardly extending portions which are pivoted upon shouldered screws 62, likewise threaded in the key plate 60. A motor bar stem 64 has its upper end positioned beneath the key bar 62 and is guided for reciprocatory movement by a pair of studs 66, 61, secured in an outer section plate 66, the studs 66 and 61 projecting through elongated slots 66 formed in the key stem 64. A tension spring 16 normally holds the'stem 64 in its uppermost position, and thus holds the motor bars 52 and 64 in their normal positions, as shown in Fig. 2, since the motor bar 62 has a pin and slot connection with the bar 54. This connection comprises a pin 12 riveted in the motor bar 62 and projecting into a slot 14 formed in the rearwardly extending arm portion of the motor bar 64. There is a similar connection between the forwardly extending left-hand portion of the motor bar 52 and the left-hand rearwardly extending arm portion .of the motor bar 54, as indicated in dotted lines in Fig. 1 and as further shown in Fig. 5.

Due to this interconnection between the bars 62 and 54, depression of either of these bars will cause the stem 64 to be moved downwardly against the tension of its spring 16. Furthermore, the operator of the machine may press upon any portion of either of the motor bars 62 or 54 to accomplish this result. This is of great convenience for skilled operators, since it enables them to initiate an operating cycle of the machine immediately following the depression of the last numeral key, irrespective of the position of such key, without moving the hand appreciably.

It will be noted that the lower end of the stem 44 overlies an insulating strip 16 attached to one of the contact arms of the switch 24, the switch 24 being suitably secured to the outer section plate 66 by a bracket 16.

Control key operated switch mechanism As above indicated, the solenoid 26 may be energized not only by depression of one of the motor bars 62 or 54, but also by operation of any one of the control keys 46.I to 46.6. As best shown in Fig. 4, each of the control keys is provided with a key stem I52, each having a forward cam projection I54. The key stems I62 are suitably guided in slots formed in key stem plates I56 and I56 and are resiliently urged to their uppermost positions, as shown in Fig. 4, by coil springs I60 which extend through a horizontal row of key stems and are anchored at their ends. One of the coil springs I66 thus serves as a key return spring for a horizontal row of keys.

The key stems I52 are also guided and the length of their strokes limited by rods I6I which project through elongated slots I63 formed in the key stems, the rods I6I extending through the slots I63 of a horizontal row of key stems and being suitably secured in position.

The cam projections I54 are adapted, upon depression of the keys 46 successively to engage slides I62, I64, as shown in Figs. 4 and 6. The key stems I52, for the keys 46.I, 46.3, 46.5, 46.1, and 46.6, engage shoulders I66 formed at the sides of these slides I62 and I64, while the key stems 52, for the keys 46.2, 46.4, 46.6. an 46.6, project through slots I66 formed in the slides I62 and I64. The slide I62 is pulled rearwardly bya tension spring I16 which is suitably tensioned between an anchoring stud HI and a lug I12 struck upwardly from the slide I62.

The forward end of the slide I64 (Fig. 8) is engageable with the upwardly extending arm I14 of alatch I 16 forming part of a bail I11. The latch I16 is urged clockwise, by a suitably anchored Spring I16, into latching engagement with a stop shoulder on a stepped actuator ba'r I60, as will be more fully described hereinafter. The spring I16 serves to urge the slide I64 rearwardly. The slide I62 has a forwardly extending projection I62, while the slide I64 has a similar but shorter forward projection I64 (Fig. 4).

The switch 44, previously described with reference to the circuit diagram of Fig. 12, is formed by a pair of resilient switch arms I65, I66 (Figs. 3 and 6). The switch arm I66 has an insulatin strip I61 riveted or otherwise suitably secured thereto, while the switch arm I66 has a similar strip of insulating material I66 secured thereto. The forward projection I62 is normally in position engaging the strip I61, while the projection I64 of the slide I64 terminates adjacent the inner surface of the insulating strip I66.

When a key, for example the key 46.6, is depressed, its camming projection I54 first moves the slide I62 forward (to the left, Figs. 4 and 6), thereby further separating the normally separated contacts of the switch 44. As the cammlng surface of the projection I54 engages the shoulder I 66 of the slide I64, the latter will also be cammed forwardly, but will move at substantially the same speed as the slide I62 until the camming projection I54 has passed beneath the slide I62, as the key stem reaches the lower limit of its stroke. When this occurs, the latching slide I62 will be pulled rearwardly (to the right, Fig. 4) by its spring I10 and its shoulder I66 will thus overlie the projection I64 and hold the key in depressed position. It will be noted, however, that when the key is in depressed position, the slide I64 will remain in its forward position so that the rearward movement of the'slide I62 will result in closure of the switch. I

As previously explained, particularly with reference to Fig. 9, the closure of the switch 44 results in the energization of the winding of the solenoid 26 and causes the operation of the machine through at least one complete cycle. In

this respect, the closure of the switch 44 has the same eil'ect as the closure oi the switch 24, since it will be noted that these two switches are connected in parallel.

The purpose of the error key 46.9 is merely to release keys (such as the numeral keys 45 or the control keys, 46.I, 48.2, and\4B.8) which havebeen accidentally or inadvertently depressed. For this reason, the slide I84 does not have a shoulder I86 to be engaged by the camming surappear hereinafter) or the repeat key 46.! will be released.

It will be understood that as long as any oi the keys 46.3 to 46.1 remains depressed, it will hold the slide I64 in its left-most (Fig. 4) position, and through the projection I84 01' the slide maintain the switch 44 closed.

A3 is more fully disclosed in my copending ap plication Serial No. 372,289, filed December 3d, 1940, the position of the stepped actuator bar I determines the character or the operating cycle of the machine, :1. e., whether it shall be an adding, subtracting, sub-total, total or other type of cycle. The subtract key does not operate any stop to limit the extent of rearward movement of the stepped actuator bar but permits it to move a full stroke rearwardly, which results in condi tioning the machine for a subtracting operation. The lower extremities of the key stems I52 for the keys 46.I to 48.! are adapted when depressed to form stops limiting the degree of rearward motion of the stepped actuator bar I80, and thus determine the character oi the ensuing cycle.

When a total, sub-total, orcredit balance is to be taken, the appropriate key 46 is depressed, and depression of this key not only results in conditioning the machine to go through a cycle or the character determined by the depressed key, but also results in'closure of the switch 44, thereby initiating an operating cycle. Itwill be understood that the character oi the cycle is determined by the distance that the stepped actuator bar Itl is permitted to move rearwardly during the first portion of the operating cycle, this distance being, oi. course, determined by the en casement of stop lugs on the stepped actuator bar with the ends of the depressed keys.

While a particular embodiment of my invention is disclosed herein, it will be apparent to those skilled in the art that numerous changes and variations may be made in the construction without departing from the underlying principles of the invention. I therefore desire, by the following claims, to include within the scope oi the invention all such equivalent structures as may be readily devised by those skilled in the art to accomplish substantially the results of my invention by substantially the same or equivalent means. 1

I claim: A

1. In an adding machine having a driving electric motor, a switch for controlling the supply .of current to said motor, said switch comprising a pair of flexible resilient contact arms, a movable control element manually movable from normal position andhaving a cam surface, a pair of slides engageable by said cam, one 01 said slides constituting a latch to hold said element displaced from its normal position, and means onsaid slides engageable respectively with said switch contact arms, whereby both of said switch arms will be flexed in the same direction by said slides during the initial portion of the movement of said control element and said switch arms will be able to move toward each other to make contact only upon movement of said latching slide to latching position.

- 2. In an adding machine having a driving electric motor, a switch tor controlling the supply of current to said motor, said switch comprising two movable parts, a manually depressible control key, a stem for said key having a saw-tooth cam projection, a pair of slides having portions lying in the path of downward movement of said cam, said slides being located suliiciently close to each other to be simultaneously engaged by said cam, the upper one of said slides serving to latch said key in depressed position, resilient means to resist movement or said slides by said cam, and means moving with said slides to engage said switch parts, moving them in the same direction as the slides aremoved by said cam projection and permitting said parts to move toward each other -as said latching slide moves to latching position over said cam projection, thereby to complete a circuit to supply current to said motor only after said key has been latched in depressed position.

3. In a calculating machine having a driving electric motor, a switch controlling the energize.- tion oi said motor, said switch comprising a pair 01 normally spaced resilient switch arms, a de pressible control key, latching means for holding said key in depressed position, and means operated by said latching means to efiect contact be tween saidswitch arms only after said latching means has moved to latching position.

4. In a calculating machine having a driving electric motor, a switch controlling the energization of said motor. a depressible key, a latch to hold said key in depressed position, and means operated by said latch to effect closure of said switch only after said latch has moved to a position in which it holds said key depressed.

5. In an adding machine having a driving elee tric motor, a motor operation controlling circuit, a switch in said circuit, a control element manually movable irom normal position, latching cam surface formed thereon, a pair of movable elements successively engaged by said cam sur-= lace upon movement oi said control member, one of said elements constituting a latch for holding said control member in its operative position, and means to elect closure or said switch only when said latter element is in latching. engagement with said control member.

'1. In a calculating machine having an electric driving motor, a motor operation controlling circuit. a switch in said circuit, said switch having two relatively movable parts, a control member manually movable from normal position to operative position, a cam on said member, and a. pair of elements cooperable with said cam and each engaging one of said switch parts, said elements being moved in the same direction by said cam during the major portion of the movement of said control member irom its normal to its operative position, and one or said elements being movable relative to the other to latch said control member in its operative position, thereby to cause relative movement of said switch part and conseqiient closure of the switch.

THOMAS O. MEHAN. 

